1. Field of the Invention
The present invention relates to a technology for appending additional information to an image and extracting additional information from an information-appended image.
2. Description of the Related Art
In recent years, information embedding technology is being developed such that additional information can be embedded in a printed literature. The additional information can be information regarding content protection of the printed literature, original digital data of the printed literature, Web pages related to the printed literature, and the like. Such additional information can be embedded by drawing certain image patterns in the printed literature.
One of the conventional methods of information embedding technology is barcode embedding. To embed a barcode, it is necessary to secure a portion for the barcode on the sheet of paper on which the printed literature is printed. However, there is a concern from a security perspective because the portion on the sheet in which a barcode is embedded can be cut off. Therefore, in another conventional technology, image patterns that are not easily noticeable are arranged in the background of the printed literature.
For example, Japanese Patent Application Laid-open No. 2002-218207 discloses an information processing device that multiplexes additional information with image information when the image information is printed on a sheet of paper. In that case, header information is generated that includes size of the additional information, an error correction code used to correct errors in the additional information, and the like.
Japanese Patent Application Laid-open No. 2005-327266 discloses a printing device that generates two-dimensional code information by arranging code information and corresponding error correction codes in a two-dimensional and distributive manner such that a printed literature on a recording medium includes the two-dimensional code information.
Japanese Patent Application Laid-open No. 2007-005935 discloses an information embedding technique in which particular kind of patterns are arranged for embedding additional information in the printed literature. Moreover, an error correction technique is used to make the patterns decodable such that the additional information can be extracted therefrom.
However, there are limitations in using error correction techniques. That is, in the case of an information loss or an error that is not correctable by using an error correction technique, then there is a possibility that incorrect information is decoded. As a result, subsequent information processing functions cannot be performed in a stable and reliable manner.